Lubricating oil additives



Uni

The present invention relates to a new class of lubricating oil additives which impart improved properties to lubricating oils containing them, and particularly relates to such additives which comprise the polymers or copolymers of alkoxy esters, and to lubricating oils containing them.

It is often desirable to improve the physical properties of lubricating oils, and one of the most useful ways of doing so is to incorporate additive compounds into the lubricating oils. The use of additives 'to improvefthedetergency of lubricating oils is well-known. Such detergent oils when used in internal combustion engines inhibit corrosion, piston ring sticking, cylinder Wear, and the formation of varnish on metal engine parts, as well as preventing the formation of sludge deposits within the engine; Well known types of detergents for lubricating oils are alkaline or alkaline earth metal-containing compounds. While such metal containing 'compounds"gnerally'have'good detergency properties, their use under certain conditions, such as severe engine conditions orwhen oil-consumption is high, may cause an undesirable residue of ash in and adjacent to the combustion chamber of the engine. The presence of such ash may reduce the engine efliciency by causing pre-ignition, valve-burning or other undesirable elfects.

It is the object of the present invention to provide an additive material which imparts good detergent properties to lubricating oils, but which does not result in the formation of harmful ash deposits within engines, and which also provides other useful properties, including raisingthe value of the viscosity index without unduly increasing the viscosity, and lowering the pour-point of lubricating oils in which the additive of the present invention is incorporated.

The additive compounds of the present invention are polymeric or copolymeric materials derived from partly esterified and alkoxylated unsaturated dibasic acids. While generally any unsaturated dibasic acid, may be used, it is preferred to usesu'bstituted or unsubstituted monoethylonic acids, such as fumaric or maleic acids which are alpha beta unsaturated or butenedioic acids or their alkyl derivatives.

The unsaturated dibasic acid is partly esterified with any aliphatic alcohol, although such alcohols having from 3 to 20 carbon atoms per molecule are preferred, and those having from 9 to 18 carbon atoms per molecule particularly preferred, The alcohols may be of straightchain or branched configuration, and those alcohols produced by the x0 process are preferred. It is within the scope of the invention to use a mixture of such alcohols.

By the term partly esterified it is meant that less than two gram molecules of alcohol is reacted with a gram molecule of organic dibasic acid during the esterification process. Particularly useful proportions of reactants include 1 gram molecule of dibasic acid with about 1.6 gram molecules of alcohol. a

The partly-esterified dibasic acid is reacted with any alkylene oxide to produce The alkylene oxido used is preferably one which contains from' 2 to 6 carbon atoms per molecule, and is particularly ethylene oxide or propylene oxide; It is within the scope the alkoxy-ester compounds.

States Patent 3,010,906 Patented Nov. 28, 1961 Well-known chemical method, forinstance at temperatures of about 140 C. and in the presence of traces of boron tri-fluoride-phenol complex. a

The additive compounds of the present invention are obtained by polymerising the alkoxy-ester compounds described above, or by copolymerizing such compounds with an unsaturated organic compound.

The preferred unsaturated organic compounds include unsaturated hydrocarbons, such as styrene, unsaturated esters derived from either unsaturated alcohols such as vinyl alcohols, or unsaturated acids such as fumaric or maleic acids, or methacrylic acid. Other unsaturated organic compounds include nitriles, e.g., acrylonitrile, or the anhydrides of unsaturated dibasic acids, such as maleic anhydride. While the above'iinsafurated'organic' compounds are the preferred compounds thealkoxy-esters may be copolymerized with, any other :copolymerizable organic compound.....

The present invention therefore comprises an oil-soluble lubricating oil additive comprising a polymer or coploymer of an alkoxy-ester, said alkoxy ester being derived from a partly esterified unsaturated dibasic acid further reacted with an alkylene oxide.

' The polymerization or coploymerization reaction of the alkoxy esters carried out by any well-known chemical process, such as low-temperature Friedel-Crafts processes,

or ionic, free radical or radiation polymerization processes.

It is preferred that the polymerization or copolymerization process be carried out with the aid of a peroxide type of catalyst, preferably benzoyl peroxide, at temperatures ranging from 50 to 150 C., for periods of time ranging from 2 to 100 hours. It may be convenient to carry out the polymerization or copolymerization process in .the presence of an inert solvent, such as gasoline, light lubricating oils, or chloroform. By the use of such solvents it is possible to control the reaction velocity and the molec-.

ular weights of the products.

To ensure that the final additive products are readily soluble in lubricating oils, it is preferable to carry out the polymerization or copolymerization reaction in the presence of an ester of maleic or fumaric acid with a C C alcohol, preferably a C -C Oxo alcohol.

The additive compounds of the present invention are intended to be used in any lubricating oil, whether derived from animal, vegetable or mineral sources, and including synthetic lubricating oils especially those comprising complex esters, diesters, formals, methacrylates, or blends thereof.

The additive compounds of the present invention may be incorporated in lubricating oils in proportions from 0.01% to 20% by weight.v

It is understood that the additive compounds of the present invention are restricted to those compounds which are soluble in the lubricating oil in which they are incorporated. Such solubility may be determined by a simple test. v

The lubricating oils containing the additive compound of the present invention may also contain other additive compounds, such as oxidation inhibitors, extreme-pressure additives and anti-frothing agents.

The invention having now been generally described, it may be further understood by reference to the following examples:

EXAMPLE I One gram molecule of maleic acid was partly esterified with 1.6 gram molecules of a C OX alcohol in the presence of l% paratoluene sulphonic acid as a catalyst. After removal of reaction water the resulting ester had an acid number of 40. l g

This ester was condensed at 140 C. with ethylene oxide in the presence of traces of a BF phenol complex. After 16 hours reaction the acid number of the ester was 6, the weight of ethylene oxide combined with the ester being equal to 8% by weight of the said ester.

The ethoxylated ester thus obtained wasfcopolytnerized' 10 with. 25% by weight of vinyl acetate at 70 C. for'an hour in the presence of 2 grammes benzoyl. peroxide.

The resulting copolymer (copolymer A) when added to a parafiinic oil having a viscosity index of 113, yielded the following results givenin Table L e Table I Percentage of copolymer A Viscosity in centistokes Viscosity Index us 32; 1 i 12s as. 4 136.6 41- New vamp

EXAMPLE II 7 One gram molecule of maleic acidwas partly esterified. with 1.5 gram molecules of a C Ono alcohol in the presence of paratoluene sulphonic acid as catalyst, and 100-220% of gasoline. After washing in water and distilling the gasoline off, an. ester was obtained having an acid number of 30. a V

This ester was condensed with gaseous ethylene oxide at 140 C. in. the presence of traces of the BF;;/ ether complex. After 18. hours reaction, the acid number was 1.1: the weight of ethylene oxide combined with the ester being equal to 7% of. the weightof the said ester.

Aiter blowing with CO at 110 C. and treating with 2% A'ctisil earth the acid number of the ester was 0.8.

The ester was then polymerized at 70 C. in the presence of 0.5% benzoyl peroxide with 50% by weight of vinyl acetate in the presence of an equal quantity of C Oxo alcohol maleofumarate. V

, The copolymer thus obtained when added to a paraffinic oil'oi viscosity index 112.5, yields the following, results given in Table II.

- Table II Characteristics of oil according to precentagc of copolymer B Percentage of copolymer B I Viscosity Viscosity in centi- Pour point,

index stokes at '0. 99 0.

0a... 112.5 5. 4 -9 n 2- 7 --1g 1 122. 5 5. 8 2- 126 6. 1 a as 4 c- 135 6. 9, s. 146 9. o

' V i The lubricant composition obtained by addition 'to the above parafiinic oil was stable at low temperature. After holding test at -5'1 C. for 48 hours with up to 20% of cop'olymer B the composition remained clear; 7

EXAMPLE 1n engine test was carried outwith a mineral oil containing copolymer B, and with, the same mineral oil without any additive.

The-test was carried out according tothe standard CRC 7 FL-Z adapted for a Peugeot 203 engine (4 cylinder, bore mm., stroke 73 mm, total stroke capacity 1290 cc., volumetric compression 6.8, speed 2500 r.p.m., length of test 50 hours, output 20 H.P.

This test is of the type known as cold test.

Without ccordlng COmpflSlhlOll 0t oils by weight Additive 1 to b invention Poratfinic oil of viscosity 35 ceutistokes at i 37.8 C. viscosity index 112, percent 99.1 95. Oopoly'rner 13, per 3. 25

Anti-oxidising agent: polymer oi di-isobutylene phenol with formaldehyde and ammonia, percent 0. 4 0. 4

Anti-corrosion additive: alpha plnene phosphosulphide, percent 0; 5 0. 6 Chief characteristics of these oils-Viscosity nd x 7 112 131 Four point, 0;- .w g --9' 7 -27 The results of the engine test are as follows:

(1) Cleanliness-The cleanliness' engine enumerated below is given points: from- 0 to 10', the point-1'0 being given'to parts having no deposit and 0 to parts totally'covered with deposit.

Ollwithout 7 Oil of additive invention Combustion chamber (deposits) 6. 9 9.3 Skirts (varnish) 7,.0 9. 4. 2. Deposits 01 mud:

grammes on oil filter 32 9 grammes in connecting rod 17 2. 3

9 carbon atoms per molecule, condensing the partial.

ester thereby formed with ethylene oxide in sufiicient amount to incorporate about 7 to 8 weight percent of ethylene oxide into the partial ester, and thereafter copolymerizing the resulting ethoxylated ester within the range of 25 to 50 weight percent of vinyl acetate in the presence of a peroxide type catalyst.

2. oil-soluble lubricating oil additive having detergency and viscosity index improving properties prepared by partially esterifying one mole of abutenedioic acid with from about 1.5 to about 1.6 moles of an aliphatic alcohol having in the range of 3 to 20 carbon atoms per molecule, condensing the partial ester: thereby formed with an alkylene oxide having. in the range of 2 to 6 carbon atoms per molecule in sufficient amount to n corporate about 1 to 8 weight percent of alkylene oxide into the partial ester, and thereafter copolyrnerizing the resulting alkoxylated ester within the range of from 25 V to 50 weight percent of viuylacetate.

3. An additive as defined by claim 2 wherein said alkoxylated ester has been additionallycopolymerized with an ester of a butenedioic. acid. 1 p

" 4. An additive asv defined by claim 2 wherein said alkoxylated ester has been copolymerized with said vinyl acetate in admixture with a C alcohol maleofumarate.

5. A lubricating composition consisting essentially. of a major proportion of a' lubricating oil and from 0.01 to .20 weight percent of the additive defined by claim 2.

' {References on following page) of the parts of the References Cited in the file of this patent 2,607,761 2,615,845

UNITED STATES PATENTS 2,616,851

2,047,398 Voss July 14, 1936 2,703,811 2,255,313 Ellis Sept. 9, 1941 2,704,277 2,384,595 Blair Sept. 11, 1945 2, 1, 2,418,688 Atwood Apr. 8, 1947 2,721,878 2,533,376 Jones Dec. 12, 1950 2 2,559,510 Mikeska et a1 July 3, 1951 2, 2,570,788 Giamman'a Oct. 9, 1951 10 2,392,790

6 Seymour Aug. 19, 1952 Lippincott et al Oct. 28, 1952 Giammaria Nov. 4, 1952 Smith Mar. 8, 1955 Giammaria Mar. 15, 1955 Popkin et a1 Oct. 25, 1955 Popkin Oct. 25, 1955 Cashman et a1 Feb. 25, 1958 Stuart et a1 June 30, 1959 Stuart et a1 June 30, 1959 

2. AN OIL-SOLUBLE LUBRICATING OIL ADDITIVE HAVING DETERGENCY AND VISCOSITY INDEX IMPROVING PROPERTIES PREPARED BY PARTIALLY ESTERIFYING ONE MOLE OF A BUTENEDIOIC ACID WITH FROM ABOUT 1.5 TO ABOUT 1.6 MOLES OF AN ALIPHATIC ALCOHOL HAVING IN THE RANGE OF 3 TO 20 CARBON ATOMS PER MOLECULE, CONDENSING THE PARTIAL ESTER THEREBY FORMED WITH AN ALKYLENE OXIDE HAVING IN THE RANGE OF 2 TO 6 CARBON ATOMS PER MOLECULE IN SUFFICIENT AMOUNT TO INCORPORATE ABOUT 7 TO 8 WEIGHT PERCENT OF ALKYLENE OXIDE INTO THE PARTIAL ESTER, AND THEREAFTER COPOLYMERIZING THE RESULTING ALKOXYLATED ESTER WITHIN THE RANGE OF FROM 25 TO 50 WEIGHT PERCENT OF VINYL ACETATE.
 5. A LUBRICATING COMPOSITION CONSISTING ESSENTIALLY OF A MAJOR PROPORTION OF A LUBRICATING OIL AND FROM 0.01 TO 20 WEIGHT PERCENT OF THE ADDITIVE DEFINED BY CLAIM
 2. 